1. Field of the Invention
The present invention relates to a heating device, a substrate processing apparatus configured to process a substrate, and a method of manufacturing a semiconductor device.
2. Description of the Prior Art
As a process using a method of manufacturing a semiconductor device such as a dynamic random access memory (DRAM), a substrate processing process in which a substrate such as a silicon wafer is heated to be processed has been performed. Such a substrate processing process has been performed by using a substrate processing apparatus, which includes a process chamber configured to accommodate a substrate to process the substrate, and a heating device configured to heat the inside of the process chamber. The heating device includes a ring shaped heating element surrounding the outer circumference of the process chamber, and a ring shaped insulating body installed along the outer circumference of the heating element. Respectively at the upper and lower ends of the heating element, a mountain part and a valley part (cutout part) are alternately connected in plurality to form a meander shape (for example, refer to Patent Document 1 below).
In addition, a heating device includes a ring shaped heating element surrounding the outer circumference of a process chamber, an insulating body installed in a manner of surrounding the outer circumference of the heating element, and a holding member configured to fix the heating element to the inner wall of the insulating body (for example, refer to Patent Document 2 below).    [Patent Document 1]    Japanese Unexamined Patent Application Publication No. 2007-88325    [Patent Document 2]    Japanese Unexamined Patent Application Publication No. H4-318923
Both ends of the above-described heating element having a ring shape penetrate a side wall of the insulating body and are fixed, and simultaneously, the respective valley parts of the heating element are independently fixed to an inner circumferential side wall of the insulating body, so that the heating element is held to the inner circumferential side of the insulating body. To fix the respective valley parts of the heating element to the inner circumferential side wall of the insulating body, a holding body configured as a pin having, for example, a bridge shape has been used. That is, both ends of the holding body are independently inserted into the ends (valley bottom parts) respectively of the valley parts adjacent to both the ends of the holding body and fixed to the inner circumferential side wall of the insulating body, so as to suppress misaligning of the heating element.
In addition, in the above-described heating device, when the heating element thermally expands while temperature is increased, the heating element contacts the insulating body, so that members thereof may be damaged. Especially, since a displacement amount of the heating element cumulatively increases as it goes away from the holding member, the heating element easily contacts the insulating body at a place distant from the holding member.
However, in the above-described configuration, when the heating element with temperature being increased is thermally deformed, the gaps between the valley parts decrease, so that a holding opening may be sheared.